Because a group communication service in which a plurality of users participate in a call simultaneously transmits the same downlink traffic to all users in a group, a downlink multicast-based or broadcast-based communication connection, as well as a unicast connection, can be used. Therefore, for a cellular based wireless access system using the group communication service, a conventional broadcast service technology, for example, a multicast broadcast service (MBS) technology or terminal-based unicast service technology, can be taken into consideration.
Application of a conventional idle mode scheme to a group communication terminal is inefficient because the conventional art is designed for a unicast service terminal or broadcast service terminal. Particularly, if there are a large number of users currently participating in group communication, and most of the users are participating in the service for the purpose of listening, uplink traffic may be limited to some specific users. Moreover, call duration of a group communication such as push-to-talk (PTT) may be substantially long, unlike a one-to-one voice service in a general public network, and a deactivation interval of voice traffic may continue for a considerably long period of time. Accordingly, if the users move and spread over many cells, unnecessary handover is performed to maintain a bidirectional connection establishment even if no group communication traffic occurs. Further, a base station maintains an unnecessary connection establishment and continuously manages information of each terminal, resulting in low efficiency and higher power consumption of a terminal.